In 1944, Weinhouse et al. (1) reported that the incubation of carboxyllabeled octanoate with rat liver slices yielded acetoacetate in which the carboxyl and carbonyl carbons were equally labeled. Random condensation of 2-carbon units resulting from ,8 oxidation was therefore offered by these workers as a possible mechanism for the formation of acetoacetic acid from octanoate. The conversion of ...

To clarify the role of insulin and growth hormone (HGH) in regulating substrate production for body fuel during prolonged starvation, 6 normal subjects and 10 HGH-deficient dwarfs were fasted for 6 days. Four of these dwarfs received HGH during the fast. Blood glucose concentration decreased a mean 15 mg/100 ml in both controls and HGH-treated dwarfs, but decreased 50 mg/100 ml in untreated dwa...

The mechanism of the biological oxidation and synthesis of fatty acids has largely been elucidated during the past few years through work in several laboratories (l-7). This work resulted in the complete confirmation of Knoop’s B oxidation theory and of the main conclusions derived from the early work of Dakin and Embden. Perhaps one of the most important aspects of the recent work is the demon...

Crossbred wether lambs were used to assess the effect of altered forage:concentrate ratio and metabolizable energy intake on metabolism of substrates by ruminal epithelium using an isolated cell system. Lambs (n = 28; 20.1 +/- 3 kg BW) were assigned randomly to a factorial arrangement of dietary treatments consisting of either 75% forage or 75% concentrate fed once daily at either .099 or .181 ...

Observations on lactate transport in brain cells and cardiac myocytes indicate the presence of a high-affinity monocarboxylate transporter. The rat monocarboxylate transporter isoform MCT2 was analysed by expression in Xenopus laevis oocytes and the results were compared with the known characteristics of lactate transport in heart and brain. Monocarboxylate transport via MCT2 was driven by the ...

(a) The reactivity of substituted acetates as substrates for CoA transferase increases sharply with increasing basicity and exhibits a slope of 1.0 in a plot of either log kappacat or log (kappacat/Km) against pKa (betanuc = 1.0). This result shows that the catalyzed reaction, which involves both carboxylate activation and leaving group transfer, does not proceed through a fully concerted react...

Cytoplasmic free NAD(+)/NADH ratios have been calculated from lactate to pyruvate ratios, and mitochondrial NAD(+)/NADH ratios, have been calculated from beta-hydroxybutyrate to acetoacetate ratios in isolated rabbit alveolar macrophages. In freshly harvested cells, assuming a pH of 7 for the two compartments, cytoplasmic NAD(+)/NADH averaged 709 +/-293 (SD), and mitochondrial NAD(+)/NADH avera...

A series of 120-600 kilobase deletions with defined endpoints were made in the 1600-kilobase Rhizobium meliloti megaplasmid pRmeSU47b, by homologous recombination between the IS50 elements of transposon insertions. Utilizing IS 50-mediated homologous recombination we also made defined reductions in deletion size and combined adjacent deletions. Deletion structure was confirmed by phage transduc...

Norepinephrine-sensitive lipase activity was measured in rat epididymal fat pads by determining release either of free fatty acids or of glycerol. Stimulation of the lipase activity by norepinephrine in vitro could not be duplicated by injecting norepinephrine into the rats before sacrifice. A reliable method for assay of lipase deactivation rate was developed in which the tissue is incubated f...

A number of instances of inhibitory effects of propionic acid on metabolic reactions have been reported. Grafflin & Green (1948) found that the oxidation of acetate by washed rabbit-kidney particles ('cyclophorase') was inhibited by propionate, which itself was not oxidized. The oxygen uptake of sheep-rumen epithelial tissue was shown (Pennington, 1954) to be markedly depressed by propionate in...